If the rough-in is just horizontal pipe with no p-trap, you will want to add it below floor (slab)level.

Enclose it in a wooden frame box and cover with preferably sand. Do not cement over it.

Make sure it connects to the 2" drain. Most tubs are 1.5" drain, but (pipe) drains below slab floors should be 2" minimum.

: The "P" trap goes under the floor, and if you should already have one and then add another, the tub will not drain. If you raise the tub and install the "P" trap above the floor you will create an "S" trap which is also illegal.

: : Hi. I'm finishing my basement.: : The rough-in for the bathtub does not include a P-trap.: : How much do I need to raise the bathtub to fit a P-trap?: : What is the minimum height of a P-trap?